Pressure seal for pumping instruments through drill rod

Abstract

A device for placement between a rotary drill motor and a drill rod for use in pumping instruments down the drill rod. The device has pressure seals at each end and an opening for an instrument cable which slides through the opening as the instruments are pumped down the drill rod.

We claim: 
     
       1. In a system for taking surveys of borehole conditions in a generally horizontal borehole being drilled, said system comprising a drill rod, a survey probe in the drill rod adapted to be pumped through the drill rod and retrieved by reeling in a cable attached to the probe, a pump for pumping fluid through the drill rod to force the survey probe therethrough, a rotary motor between the pump and the drill rod, and a pipe extending from the rotary motor in alignment with the drill string; the improvement wherein a sealing device positioned between said pipe and said drill rod is provided, said sealing device comprising: (a) a housing having a central flow passage therethrough and an enlarged recessed opening in each end therethrough, said housing being of split construction and having two half sections;   (b) a first seal in one end of said housing adapted to sealingly engage said drill rod when pressed thereagainst;   (c) a second seal in the other end of said housing adapted to sealingly engage said pipe when pressed thereagainst;   (d) an instrument cable entrance opening extending from outside said housing to said flow passage, said opening being bisected by the connecting plane of said two half sections, said opening being at an acute angle with respect to said flow passage; and   (e) packing means in said opening allowing movement of an instrument cable therethrough and preventing leakage therefrom.     
     
     
       2. A sealing device comprising: (a) a housing having an axial flow passage therethrough and an enlarged recessed opening in each end thereof, said housing being split along its longitudinal axis and formed of two half sections joined together;   (b) a sealing gasket in said recessed opening at each end of said housing adapted to sealingly engage a pipe pressed thereagainst in alignment with said flow passage;   (c) a bore through said housing in fluid communication with said flow passage and at an acute angle therewith, said bore being partially formed in each of said half members; and   (d) packing means in said bore for sealingly engaging a cable extending therethrough.